scholarly journals Late Stages of Stellar Evolution

1995 ◽  
Vol 166 ◽  
pp. 173-180
Author(s):  
P. Thejll
Keyword(s):  
Stellar Evolution ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
High Accuracy ◽  
Current Understanding ◽  
Large Numbers ◽  
Hot Subdwarfs ◽  
Late Stages ◽  
Central Stars

A review is given of the use of high-accuracy astrometry on research on white dwarfs and the hot subdwarfs and central stars of planetary nebulae (CSPN). Predictions are made about the expected impact of HIPPARCOS, and the possible impacts of GAIA and ROEMER. Discovery of large numbers of new white dwarfs is expected, and, for the more distant hot subdwarfs and CSPN, important refinements of our current understanding of these objects. For white dwarfs independent values of mass and radius may be accurate enough to allow new understanding of the internal composition.

scholarly journals Spectra of the Central Stars of Planetary Nebulae

1968 ◽  
Vol 34 ◽  
pp. 339-354 ◽  
Author(s):  
Lawrence H. Aller
Keyword(s):  
Observational Data ◽  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Spectroscopic Observations ◽  
Theoretical Investigations ◽  
Late Stages ◽  
Central Stars

The central stars of planetary nebulae represent seemingly well-defined late stages of stellar evolution. Theoretical investigations with predictions of evolutionary tracks impose difficult requirements for observational data. Measurements of spectral energy distributions, of colors, and of magnitudes, and spectroscopic observations are all urgently needed.

scholarly journals Cluster analysis of the hot subdwarfs in the PG survey

1989 ◽  
Vol 114 ◽  
pp. 130-133
Author(s):  
Peter Thejll ◽  
Darryl Charache ◽  
Harry L. Shipman
Keyword(s):  
Cluster Analysis ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Galactic Latitude ◽  
Gravitational Lenses ◽  
Population Parameters ◽  
High Galactic Latitude ◽  
Space Density ◽  
Hot Subdwarfs ◽  
Late Stages

The Palomar Green survey (Green et al., 1986) of faint blue, high galactic-latitude objects, turned up several interesting new classes of objects, such as gravitational lenses (Weyman et al., 1980), the ultra hot star H1504+65 (Nousek et al., 1986), and the PG 1159-035 variables (McGraw et al., 1979). The PG survey forms a mainstay in the investigations of late stages of stellar evolution. Work (Flemming et al., 1986) has already cast light on the important question of the space density of DA’s and continuing work is seeking values for similar population parameters for the subdwarfs: Evolutionary links between the subdwarf stage and white dwarfs will thereby be illuminated.

scholarly journals 12. The Nuclei of Planetary Nebulae as Progenitors of White Dwarfs

1971 ◽  
Vol 42 ◽  
pp. 77-78
Author(s):  
C. R. O'Dell
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
White Dwarfs ◽  
Rapid Change ◽  
Planetary Nebulae ◽  
Review Article ◽  
The Past ◽  
The Subject ◽  
Central Stars

Stellar evolution is characterized by fast and slow phases. Usually the periods of rapid change are difficult to follow observationally; but, this does not seem to be the case when passing through the planetary nebula stage. Because of their high intrinsic luminosities and easy identification, it is possible to identify and study these objects and their central stars rather completely. It is quite relevant to discuss these objects at a symposium on white dwarfs since the central stars may be in the immediate progenitor stage before white dwarfs. The actual picture of the evolution of the nuclei has changed rather little in the past few years and is the subject of an earlier review article (O'Dell, 1968) to which the reader is referred.

scholarly journals Catalogue of the central stars of planetary nebulae

2020 ◽  
Vol 640 ◽  
pp. A10
Author(s):  
W. A. Weidmann ◽  
M. B. Mari ◽  
E. O. Schmidt ◽  
G. Gaspar ◽  
M. M. Miller Bertolami ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Late Stage ◽  
Planetary Nebulae ◽  
Surface Gravity ◽  
Physical Parameters ◽  
Evolutionary Models ◽  
Pertinent Information ◽  
Central Stars ◽  
Statistical Improvement ◽  
Magnitude Estimates

Planetary nebulae represent a potential late stage of stellar evolution, however, their central stars (CSPNe) are relatively faint and, therefore, pertinent information is available for merely < 20% of the Galactic sample. Consequently, the literature was surveyed to construct a new catalogue of 620 CSPNe featuring important spectral classifications and information. The catalogue supersedes the existing iteration by 25% and includes physical parameters such as luminosity, surface gravity, temperature, magnitude estimates, and references for published spectra. The marked statistical improvement enabled the following pertinent conclusions to be determined: the H-rich/H-poor ratio is 2:1, there is a deficiency of CSPNe with types [WC 5-6], and nearly 80% of binary central stars belong to the H-rich group. The last finding suggests that evolutionary scenarios leading to the formation of binary central stars interfere with the conditions required for the formation of H-poor CSPN. Approximately 50% of the sample with derived values of log L⋆, log Teff, and log g, exhibit masses and ages consistent with single stellar evolutionary models. The implication is that single stars are indeed able to form planetary nebulae. Moreover, it is shown that H-poor CSPNe are formed by higher mass progenitors. The catalogue is available through the Vizier database.

Large planetary nebulae and their significance to the late stages of stellar evolution

1990 ◽  
Vol 359 ◽  
pp. 392 ◽  
Author(s):  
James B. Kaler ◽  
Richard A. Shaw ◽  
Karen B. Kwitter
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Late Stages

scholarly journals NLTE analysis of central stars of highly excited Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 132-132
Author(s):  
T. Rauch ◽  
J. Köppen ◽  
R. Napiwotzki ◽  
K. Werner
Keyword(s):  
White Dwarfs ◽  
State Of The Art ◽  
Planetary Nebulae ◽  
Evolutionary Status ◽  
Agb Stars ◽  
Spectral Analyses ◽  
Central Stars

Very hot central stars (CSPN) of highly excited planetary nebulae (PN) display directly the formation of white dwarfs. Only a few of these CSPN have been analyzed so far due to their low brightness and thus, the interpretation of their evolutionary status is hampered by statistical incompleteness. In the last decade many spectral analyses of very hot post-AGB stars by means of state-of-the-art NLTE model atmospheres have been performed (e.g. Rauch et al. 1996; Werner & Rauch 1994; Rauch & Werner 1995) and our picture of post-AGB evolution has been improved.

scholarly journals A High Resolution Far-UV Spectral Atlas of CSPNs and Hot White Dwarfs

1993 ◽  
Vol 155 ◽  
pp. 91-91
Author(s):  
R.W. Tweedy
Keyword(s):  
High Resolution ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolutionary Sequence ◽  
Spectroscopic Analyses ◽  
Spectroscopic Information ◽  
The University ◽  
Phd Thesis ◽  
Central Stars

A high-resolution IUE spectral atlas of central stars of planetary nebulae and hot white dwarfs has been produced (part of Tweedy, 1991, PhD thesis from the University of Leicester, UK), and examples from it are shown here. It has been sorted into an approximate evolutionary sequence, based on published spectroscopic analyses, from the cool 28,000K young central star He 2–138, through the hot objects like NGC 7293 and NGC 246 at 90,000K and 130,000K respectively, down to 40,000K DA white dwarfs like GD 2, which is the chosen cutoff for this selection. Copies of a revised version of this atlas, which will include more recent spectroscopic information and also white dwarfs down to 35,000K – to include the Si III object GD 394 – will be sent to anyone who requests one.

scholarly journals The EREBOS project: Investigating the effect of substellar and low-mass stellar companions on late stellar evolution

2019 ◽  
Vol 630 ◽  
pp. A80 ◽  
Author(s):  
V. Schaffenroth ◽  
B. N. Barlow ◽  
S. Geier ◽  
M. Vučković ◽  
D. Kilkenny ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
Eclipsing Binaries ◽  
Atmospheric Parameter ◽  
Reflection Effect ◽  
Common Envelope ◽  
Period Distribution ◽  
Hot Subdwarfs ◽  
Substellar Companions ◽  
Central Stars

Eclipsing post-common-envelope binaries are highly important for resolving the poorly understood, very short-lived common-envelope phase of stellar evolution. Most hot subdwarfs (sdO/Bs) are the bare helium-burning cores of red giants that have lost almost all of their hydrogen envelope. This mass loss is often triggered by common-envelope interactions with close stellar or even substellar companions. Cool companions to hot subdwarf stars such as late-type stars and brown dwarfs are detectable from characteristic light-curve variations – reflection effects and often eclipses. In the recently published catalog of eclipsing binaries in the Galactic Bulge and in the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey, we discovered 125 new eclipsing systems showing a reflection effect seen by visual inspection of the light curves and using a machine-learning algorithm, in addition to the 36 systems previously discovered by the Optical Gravitational Lesing Experiment (OGLE) team. The Eclipsing Reflection Effect Binaries from Optical Surveys (EREBOS) project aims at analyzing all newly discovered eclipsing binaries of the HW Vir type (hot subdwarf + close, cool companion) based on a spectroscopic and photometric follow up to derive the mass distribution of the companions, constrain the fraction of substellar companions, and determine the minimum mass needed to strip off the red-giant envelope. To constrain the nature of the primary we derived the absolute magnitude and the reduced proper motion of all our targets with the help of the parallaxes and proper motions measured by the Gaia mission and compared those to the Gaia white-dwarf candidate catalog. It was possible to derive the nature of a subset of our targets, for which observed spectra are available, by measuring the atmospheric parameter of the primary, confirming that less than 10% of our systems are not sdO/Bs with cool companions but are white dwarfs or central stars of planetary nebula. This large sample of eclipsing hot subdwarfs with cool companions allowed us to derive a significant period distribution for hot subdwarfs with cool companions for the first time showing that the period distribution is much broader than previously thought and is ideally suited to finding the lowest-mass companions to hot subdwarf stars. The comparison with related binary populations shows that the period distribution of HW Vir systems is very similar to WD+dM systems and central stars of planetary nebula with cool companions. In the future, several new photometric surveys will be carried out, which will further increase the sample of this project, providing the potential to test many aspects of common-envelope theory and binary evolution.

scholarly journals Binary Central Stars of Planetary Nebulae

Galaxies ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 28 ◽  
Author(s):  
David Jones
Keyword(s):  
Planetary Nebulae ◽  
Current Understanding ◽  
Intermediate Mass ◽  
Single Star ◽  
Intermediate Mass Stars ◽  
Binary Evolution ◽  
Central Stars

It is now clear that a vast majority of intermediate-mass stars have stellar and/or sub-stellar companions, therefore it is no longer appropriate to consider planetary nebulae as a single-star phenomenon, although some single, isolated stars may well lead to planetary nebulae. As such, while understanding binary evolution is critical for furthering our knowledge of planetary nebulae, the converse is also true: planetary nebulae can be valuable tools with which to probe binary evolution. In this brief review, I attempt to summarise some of our current understanding with regards to the role of binarity in the formation of planetary nebulae, and the areas in which continued study of planetary nebulae may have wider ramifications for our grasp on the fundaments of binary evolution.

Sign in / Sign up

Export Citation Format

Share Document